I have an existing Wireless network that has been running for about a year now with no problems ever.

The network has a base Dlink Wifi router that serves all the different PCs with Wifi.

Today I have purchased two Airport Express` and set one up to stream audio from my iTunes and another to share a printer.I have set these up to simple connect to the existing Network (not extend the network)

The problem I have is that as soon as one (or both) of these are on it will run for a few minutes and the cause the Dlink router to Crash? The Dlink router will the restart and work for a few more minutes and crash once more - this cycle repeats itself over and over.

As soon as I plug out the airport express the Dlink router functions fine and will not restart - even for many hours with a high load.
This happens with both the Airport Express` that I have.